This invention relates to a solar heating system. More particularly it relates to a solar heating system comprising a combined solar collector, liquid chiller, and storage tank, featuring a movable thermally actuated interior insulated panel. Most solar heating systems in the prior art have used flat plate collectors separate from a storage tank. These systems usually require a pumping action to move hot fluid from the collector into a storage tank which is lower than the collector. Also, the collectors are subject to freezing unless complicated evacuation systems are provided or expensive nonfreeze fluids are used.
There have been some systems which have combined collectors and storage tanks, e.g., the Steve Bear house in Arizona or the Harold Hays "Skytherm" house. These systems are usually equipped with external insulation which require physical manipulation to make the system work. They also limit the heater to a southern wall or ceiling, thus the structure must be built to suit the needs of the collector.
Thermal diodes have also been offered as a means to keep energy in storage ("Proceedings of the Workshop on Solar Energy Storage Subsystems for Heating and Cooling of Buildings", Apr. 16-18, 1975, NSF-RA-75-041, page 141, "Storage Aspects of Thermic Diode Solar Panels".). For these systems to work, piping must be incorporated into the collector and employed very carefully. Thermal diodes also do not eliminate freeze unless expensive nonfreeze fluids are used. The boiling and freezing of the fluid in the collector has always been a problem with solar energy heating systems. The present invention neatly solves the problem by utilizing a movable insulated panel inside the storage tank. In the collecting mode the interior panel is moved away from the storage tank wall thus forming a solar collector composed of a transparent thermal cover, the tank wall, the working fluid and the movable interior panel. The fluid moves from the tank and through the collector and back to the tank by natural circulation. The chilling mode is similar to the collecting mode with the transparent cover removed such that heat radiates from the tank wall to the environment. In the storage mode the movable interior insulated panel is moved up flush to the tank wall thus eliminating the collector fluid flow path and evacuating practically all fluid from the collector. In the storage mode heat transfer between the tank fluid and the tank environment is essentially eliminated thus precluding possibility of freezing or boiling of the fluid.